What is the solution? y=-x+21 y=-2x+30 a. (8,12) b. (9,11) c. (8,11) d. (9,12)

Monitors manufactured by tsi electronics have life spans that have a normal distribution with a standard deviation of 1800 hours and a mean life span of 20,000 hours. if a monitor is selected at random, find the probability that the life span of the monitor will be more than 17,659 hours. round your answer to four decimal places.